The present invention relates to electronic video reproduction systems and more particularly to methods and devices for preventing unauthorized duplication of electronic video presentations.
The present invention is described as it relates to digital movies and their presentation in theatres, however it should be understood to be equally applicable to other digital video presentations methods and systems.
A major problem with digital movies today is piracy, or the unauthorized reproduction thereof. Pirated copies of movies can be found on film and other electronic media, such as video tape, or magnetic or optical disk. Pirated movies are sold around the world and shown without any royalties being paid to the proper persons, e.g. the originators or studio. Accordingly, it is desirable that electronic video presentation systems be as secure as possible and as immune to piracy as possible.
In an electronic video presentation system dedicated to showing digital movies or video presentations, data representative of the movie or video presentation is relatively secure for most parts of the system. FIG. 1 illustrates such a system 10. In referring to the figures, like references designate like elements of the invention.
Referring to FIG. 1, a video presentation such as a movie is typically prepared at a location 20 such as a studio. The movie is typically displayed at a distinct location 30 such as a theatre. Using conventional processing elements 40 at the studio 20, a movie is captured and digitized, and compressed into a bitstream which is then encrypted to provide a secured, digital bitstream 50. The movie is reproducible from the bitstream 50. The encrypted bitstream 50 is transported to a remote location 30 by some means, such as a computer network or physical medium like a magnetic tape or disk, for example. In a theatre 30, the encrypted bitstream 50 is decrypted and decompressed using conventional processing elements 60. The decrypted, decompressed bitstream 70 is fed to projector 80 which displays it on a movie screen for example.
The physical studio 20 can be secured so as to protect the movie from being pirated. Between the studio 20 and theatre 30, the bitstream 50 is encrypted. Hence, even if the bitstream 50 is intercepted or stolen, sufficiently robust encryption techniques exist and are used to prevent easy reproduction of pirated copies of the movie. Within the theatre 30, decryption and decompression, using elements 60, happen almost simultaneously. This typically is provided on the same computer platform which can also be made sufficiently secure using conventional locked housings, or enclosures.
However, over the transmission link between decryption and decompression by elements 60 and projector 80, decrypted and decompressed signal 70 is conventionally a xe2x80x9cclearxe2x80x9d signal that can potentially be intercepted and stolen using appropriate equipment.
It is an object of the present invention to prevent theft or unauthorized duplication of signal 70 of a video presentation such as a movie.
A system and method for operating the system for deterring unauthorized reproduction of a video presentation including a plurality of images to be displayed, the system including: an encoder including: a first memory having a first plurality of addressable memory locations for storing at each of the locations data corresponding to a portion of at least one of the images to provide an array of data; and, a randomizer for pseudo-randomly addressing the first memory to provide a pseudo-random data signal corresponding to the one of the images; and, a decoder including: a second memory having a second plurality of addressable memory locations; and, a derandomizer for receiving the pseudo-random data signal and for pseudo-randomly applying the received data to the second plurality of memory locations corresponding to the original memory location array in the first memory to provide the array of data as stored in the first memory in the second memory locations and being capable of being conventionally addressed to provide a signal for reception by a display device.